I unfortunately have the dreaded code 52 on my 91 pickup with the 3vze. Motor was rebuilt 9k miles ago with new oem sensor and pigtail. Ended up having to pull the heads and machine down after machine shop did terrible work. Now I have the code 52 anytime I get the rpms up past 1600ish. I can turn it off and the code will go away until I get the rpms past that point then stays on till I turn truck off.
I don't think it would be the sensor or pigtail but i am curious what people are using to replace the shielded wire from pigtail to ecu? I've read through the forums but nobody says what kind of wire they use other than shielded. Does guage matter??
Also where is the best place to ground out the shield? On the brown wire with the rest or can I just go to the ecu mounting bolts?
If it turns out to not be wiring I'm afraid it is the ecu and am looking for suggestions on the best place to get one or send mime off to be repaired. Any help is appreciated greatly.

 

I used aircraft grade coax cable on mine. Can ground either end but not both. I still have my original ecu, runs great.